Anuria Definition

From the word itself, you can derive its definition. The prefix “a-“ or “an-“ means absence. Uria refers to urine. So by the context of the word, anuria or anuresis means no urination.

But in the clinical setting, this is actually not the case. Medically, anuria means having a urine output of less than 100 mL per day. The kidneys do not totally stop producing urine. If the kidneys stop functioning, the person dies.

The term anuria was coined in order to denote that the urine output is dangerously low. If untreated, it can be a cause of death.

Anuria is almost always associated with the term oliguria. Oliguria means having a urine output of less than 500 mL per day. It is an early sign of kidney problems. Anuria comes in late, when the disease progresses and if it is in its advanced state. Obviously, anuria is worse than oliguria.

Anuria Causes

Prerenal Causes

Prerenal causes of anuria refer to problems of the structures “before the kidneys,” i.e. the blood vessels that supply the kidneys.

The kidneys are very vascular organs, especially its medullary part. If the blood supply to the kidneys is low, it means other organs are in dire need of blood and oxygen supply, hence, the kidney which is an organ of elimination, receives less.

Postrenal Causes

Postrenal causes of anuria refer to the problems of the structures “after the kidney,” i.e. obstruction of urine flow.

There is no problem with renal perfusion and there is no noted renal disease. The problem most likely lies on urinary obstruction. The urine cannot pass through structures as it should be so there will be less urine output.

In children and neonates, the following are the postrenal causes of anuria [3]:

Stenosis of urinary meatus

Posterior urethral valves

Bilateral ureteral obstruction

Neurogenic bladder

Treatment for Anuria

Cardiopulmonary Resuscitation

Fluid resuscitation of 250-500 mL aliquots may be the key in order to increase urine output and stabilize heart rate and blood pressure. The goal is for the patient to have a urine output of at least 0.5 mL/kg/hr.

Nephrotoxic drugs

If the patient is taking drugs that are toxic to the kidneys (as noted above), discontinue these medications. It is also important to release the obstruction, decrease intra-abdominal pressure, and treat underlying infection.

Hyperkalemia is a medical emergency wherein potassium level reaches >6.5 mmol/L and ECG shows peaked T waves and widened QRS complexes. It may also be accompanied by ventricular arrhythmias and asystole.

In the presence of hyperkalemia, BLS/ALS is initiated above all. Discontinue medications and infusions that contain potassium.

Administer 10 mL of calcium gluconate 10%; 50 mL of glucose 50%; and 10 units of rapid-acting insulin. 100 mmols of sodium bicarbonate 8.4% and inhaled beta-2 agonist are also given. These will shift the potassium into the cells. However, potassium still leaks out of the cells therefore these are not permanent treatment for hyperkalemia. Excess potassium need to be excreted from the body in order to eradicate its signs and symptoms.

For a less severe case of hyperkalemia, i.e., potassium levels of 5.5-6.5 mmol/L, potassium is restricted and resonium 15-30 g should be administered [1].

Treatment for Anuria in Children

Neonates and children are more prone to dehydration than adults so this is one of the things the health care providers should watch out for.

Dehydration in children is treated by 20 mL/kg fluid bolus of normal saline solution or lactated Ringer’s solution. In cases of fluid overload, fluid restriction and furosemide (diuretics) therapy is ordered. If the cause is postrenal (obstruction or stenosis), perform urinary catheterization [3].